Sensing apparatus for inclinometers

ABSTRACT

An apparatus for sensing the orientation of an inclinometer in both direction and magnitude for determining the velocity and direction of currents in a body of water having a magnetic north seeking sphere buoyantly supported in a housing. Implanted on the sphere is a plurality of tuned circuits of different resonant frequencies set at right angles to each other and a sense-drive winding or coil mounted about the housing. Upon applying a series of pulses of voltage to the sense-drive coil, the tuned circuits will oscillate with decaying amplitude at their resonant frequencies in the intervals between the pulses of voltage. The mean voltage across each of the tuned circuits is a measure of the amount and direction of tilt of the housing caused by the currents. The sense-drive coil senses these voltages across the tuned circuits and between the induced pulses of voltages, will transmit them to conventional recording equipment whereby a continuous determination of the currents velocity and direction are obtained.

BACKGROUND OF THE INVENTION

1. Field Of The Invention

This invention relates to devices for measuring current velocity anddirection in a body of water and is more particularly directed to suchan apparatus that utilizes the direction and magnitude of tilt effectedby the current thereon for determining current velocity and direction offlow.

2. Description Of The Prior Art

In recent years, the inclinometer or tilt meter has replaced the rotormounted logs for determing subsurface current velocities and directionsin a body of water. The inclinometers are more accurate in obtaining theinformation desired and not subject to fouling by debris, and othermatter in the water as are the rotor mounted logs. From theinclinometers the extent of tilt effected by the current is obtained inboth the North-South direction and the East-West direction, whichinformation is sufficient to determine, by the application of themathematics of vectors, the actual direction of the flow of the currentand its velocity. The problem with the use of inclinometers or tiltmeters has been in the procuring of this information from these devicesat the same time as the instruments are affected by the currents. Atpresent, the inclinometers have to be lifted from their position in thebody of water in order to read the recordings thereof. As shown by myU.S. Pat. No. 3,372,585, the inclinometer is provided with a solublemember which upon its dissolution by the water after a predeterminedperiod of time, the mechanism of the inclinometer is locked in positionand the reading then recorded becomes fixed so that upon withdrawing thetilt meter from the water, the device remains inoperative and thereading unchanged. However, the device must be removed from the body ofwater to be read so that the information may be recored as incurredthereon by the action of the current. In those inclinometers wherein anumber of such readings of current action is desired over a period oftime, the devices are provided with photographic equipment for takingpictures of the readings on the inclinometer along with a clock forindicating time. These devices, likewise, must be removed from the bodyof water in order to obtain the current information. The presentinvention avoids the disadvantage of having to remove the inclinometerfrom the body of water by transmitting the readings of the devicesimultaneously as they are effected by the currents as to their forcesand directions. The recipient of this information can be ashore or in aboat and if desired the information can be recorded and stored on amagnetic tape for use in a computer.

SUMMARY OF THE INVENTION

Therefore, a principal object of the present invention is to provide anapparatus for sensing and simultaneously transmitting the effect of theorientation of an inclinometer or tilt meter by the forces of a currentin determining the velocity and direction of flow of currents in a bodyof water without removal of the device from the water.

Another object of the present invention is to provide a sensingapparatus for inclinometers or tilt meters on which electrical circuitsare mounted so that upon the orientation of the inclinometer by theaction of a current acting thereon, the electrical circuits areappropriately affected and transmit information obtained therebydetermining the current velocity and direction without the necessity ofremoving the inclinometer from the body of water.

A further object of the present invention is to provide a sensing andtranmitting apparatus for inclinometers or tilt meters in which aplurality of circuits of different resonant frequencies are mounted on amagnetically oriented sphere that is constantly aligned in a verticalposition and with the magnetic north pole in a body of water and asense-drive coil that is mounted on the housing tilted by the forces ofthe current in both magnitude and direction, which information isreceived and recorded without the necessity of removing the inclinometerfrom the body of water.

A still further object of the present invention is to provide anapparatus for inclinometers or tilt meters for sensing and recording onmagnetic tape, the magnitude and direction of tilt simultaneously withthe happening, which information is a measure of the current forces anddirection without the necessity of removing the inclinometer or tiltmeter from the body of water.

With these and other objects in view, the invention will be bestunderstood from a consideration of the following detailed descriptiontaken in connection with the accompanying drawings forming a part ofthis specification, with the understanding, however, that the inventionis not confined to any strict conformity with the showing of thedrawings but may be changed or modified so long as such changes ormodifications mark no material departure from the salient features ofthe invention as expressed in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

In the Drawings:

FIG. 1 is a perspective view of a ship in a body of water using myinclinometer for determining the current force and direction.

FIG. 2 is an enlarged perspective view of the combined housing andinclinometer with the housing partially broken away.

FIG. 3 is an exploded view of the inclinometer.

FIG. 4 is a perspective view showing the inner sphere in dotted linesand the tuned circuits in solid lines.

FIG. 5 is a cross sectional view of the inclinometer.

FIG. 6 is a diagram of the tuned circuit.

FIGS. 7-14 inclusive are plan views of the various signal wave forms.

FIG. 15 is a view similar to FIG. 5 showing an alternate construction ofmy inclinometer.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings wherein like numerals are used to designatesimilar parts throughout the several views, the numeral 10 refers to aconventional hollow cylindrical housing for containing a tilt member 11in the chamber 12 of the housing 10 whose ends are sealed by covers 13and 14. The cover 13 is removable being secured to the end of thehousing 10 by means of fasteners (not shown).

Mounted on the removable cover 13 and extending upwardly in the chamber12 of the housing 10 is the tilt meter or inclinometer 11 consisting ofa sphere 16 neutrally buoyant in a fluid 17 contained in a larger hollowspherical housing 18. The fluid 17 compeletely enshrouds the sphere 16so that there is a layer of fluid interposed between the two spheresthereby reducing friction therebetween to an absolute minimum. Thespherical housing 18 is secured to the cover plate 13 by a base member20 cemented to the cylindrical housing at one end and to the cover plate13 at the other end. The base member 20 is hollow to receive aconventional photo sensing device 23 in vertical alignment with a secondphotosensing device 24 mounted in a bracket 25 and positioned above thespherical housing 18.

Wound about the outer sphere 18 in a horizontal plane passing throughthe center of the sphere 18 are coils of wire 26 forming a drive-sensecircuit -A-. The coils 26 are connected by a wire 27 that extendsthrough a watertight opening 28 along with wires 29 and 30 connected tothe photo electric sensing devices 23 and 24. The wires 27, 29 and 30extend to voltmeters, oscilloscope for visual reading or other suitableelectronic processing circuitry capable of producing signals forrecording as on magnetic tape.

The sphere 16 is provided with a pair of tuned circuits -B- and -C- ofdifferent frequencies, with each of these circuits consisting of coilsof wire 31 and 32 respectively extending about the surface of the sphere16. The coils 31 and 32 lie in great circles about the sphere 16 atright angles to each other. A bar magnet 19 is mounted horizontallybelow the center of the sphere 16 with its ends secured to the innersurface of the sphere 16. The bar magnet 19 lies in coplanar relationwith the coil 31 and is at right angles to a line passing through theposition of the crossing of the coils 31 and 32 at the zenith -M- andnadir -N-. As a result of this arrangement of parts, the sphere 16 iscompelled to always be vertically disposed and oriented to the magneticnorth pole of the earth, notwithstanding the effects of current velocityand force subjected on the housing 10. The drive sense-coil 26 of thecircuit -A- lies in a great circle about the spherical housing 18 in aplane parallel with the plane of the magnet 19 when the instrument is inthe upright position. Each of the inductance coils 31 and 32 areconnected in series with a capacitor 40, so that each of the tunedcircuits 31 and 32 will respond to a current flowing in the drive-sensecoil 26.

The surface of the sphere 16 is divided into four quadrants 33, 34, 35and 36; quadrants 33 and 35 being painted black while quadrants 34 and36 are painted white. These quadrants may be black, white, or otherwiseoptically contrasting. The black quadrant 33 extends about the sphere16, bounded by the coil 31 on two sides and at its third side by thegreat circle 37 that is perpendicular to the axis of the sphere 16passing through the zenith -M- and nadir -N-. The white quadrant 34 isopposite the black quadrant 33 bordered by the coil 31 on two sides andthe great circle 37 on its third side. The black quadrant 35 and whitequadrant 36 are below the great circle 37 and positioned opposite eachother with the coil 32 bordering on the two sides of the quadrants 35and 36 and the great circle 37 on their third side.

Upon applying a series of impulses of electric current at regularintervals of time through the drive-sense coil 26 there will be inducedin each of the tuned circuits -B- and -C- decaying oscillation ofvoltage which, in the intervals between the applied impulses of current,will induce back into the sensing circuit a signal whose voltage is ameasure of the amount of tilt of the spherical housing 18. Since thetuned circuits are of different frequencies, two signals will be inducedin the sensing circuit to indicate tilt in two directions, namelyNorth-South and East-West and as explained in detail hereinafter, thisinformation will be sufficient to indicate direction and magnitude oftilt which is a measure of direction of flow and the velocity of thecurrent effecting that particular tilt of the inclinometer.

When the combined cylindrical housing 10 and inclinometer 11 are placedin a body of water in which there is no current present, the housing 10and the sphere 16 and spherical housing 18 will become verticallydisposed with the inner sphere 16 oriented toward the magnetic northpole. Now when pulses of electric current is applied to the coil 26 thedrive-sense circuit -A- by way of the wire 27 a magnetic field iscreated about the coil 26. There will be no current induced in the tunedcircuit -B- because the coil 31 of the tuned circuit -B- is at exactlyright angle to the drive-sensor coil 26 and thereby inducing no voltagetherein. Therefore, no signal will be returned to the conventionalsignal receiving equipment such as the oscilloscope. However if there isa current flow in the body of water as shown in FIG. 1, the housing 10and inclinometer 11 will tilt in the direction of the flow of current sothat now the spherical housing 18 will tilt with relation to the sphere16 which will always be found exactly vertically disposed and orientedto the magnetic north pole. Now the periodic electric current pulsesapplied to the sensing circuit -A- through the wire 27 will induce avoltage in the tuned circuits -B- and -C- since the coils 31 and 32 ofthe tuned circuit -B- and -C- are no longer at right angle to the coil26 of the drivesense circuit -A- but at an angle thereto. The momentarymagnetic field caused by the impressed current in the coil 26 induces avoltage pulse in the coils 31 and 32 proportional to the sine of theangle of tilt between the coils 26 and 31 and the coils 26 and 32, sothat the greater the tilt the higher the voltage and, of course, theangle and direction of flow of the water current. Between the periodicpulses of electric current impressed on the drive-sense circuit -A-, theinduced voltages in the circuits -B- and -C- will effect a decayingsignal return of amplitude commensurate with amount of tilt. Thecircuits -B- and -C- are of different resonant frequencies and so can bedistinguished, whereby the amount of tilt in each of the North-South andEast-West directions can be distinguished and ascertained. FIGS. 7 and 8reveal the wave form seen on an oscilloscope of the individual decayingvoltages effected by the circuits -B- and -C- which are resonating atdifferent frequencies, the amplitude of these wave-forms beingdetermined by the angle or component of tilt in the North or Southdirection and East or West direction respectively. These two componentsas vectors when combined will result in the actual direction in theNorth-South area or East-West area and magnitude or force of the currentthat effected the tilt of the inclinometer. The photo-sensing devices 23and 24 are used to discriminate as to which of the two directions thetilt has occured. If the housing 10 and 18 tilt to the north-east, photosensing device 23 will be viewing the black quadrant 35 and the device24 will view the white quadrant 34 to send the appropriate signals toindicate same. If the water flow is to the north west, the device 10will tilt to the north west so that the photo sensing device 24 willview the black quadrant 33 and the device 23 will view the blackquadrant 35. If the water flow is to the south east the device 23 willview the black quadrant 35 and the device 24 will view the whitequadrant 34, and if the water flow is to the sourth west, the device 23will view the white quadrant 36 and the device 24 will view the whitequadrant 34.

Now, the direction and the force of the current causing the tilt can beascertained by the apparatus 10, since the drive sensor circuit 26delivers two signals of different frequencies that are a measure of theamplitude of tilt in the north-south and the east-west directions andthe photo sensors 23 and 24 discriminate between north and south andbetween east and west to permit the determination of the current as todirection and force. FIGS. 7 to 14 inclusive show the wave formsproduced by the coils 26 for the particular orientations as indicated oneach of the Figures.

As an alternate construction of my inclinometer 11, the use of thephotosensing devices 23 and 24 can be omitted as well as the need fordividing the inner sphere 16 into black and white quadrants. In lieuthereof, as shown by FIG. 15, the spherical housing 18 is provided withtwo sets of coils or windings 41 and 42 lying in a great circle aboutthe sphere 18 at right angle to each other and to the coil 26 of thedrive circuit -A-. The coils 41 and 42 are connected by wires 43 and 44respectively, which wires extend with the wire 27 through the opening 28in the cover 13 to the aforementioned electronic equipment (not shown)on a boat or on shore. The coil 31 and 41 are in coplanar relation asare the coils 32 and 42 when the spherical housing 18 is in a verticaland neutral position as shown by FIG. 15.

With the spheres 16 and 18 in the positions shown by FIG. 11, uponapplying a periodic pulses of electric current to the drive circuit -A-,there will be no voltages induced in the circuits -B- and -C- sincetheir respective coils 31 and 32 are exactly at right angle to the coil26 of the drive circuit -A-.

Upon the inclinometer 10 being tilted by the force of a current so thatthe spherical housing 18 rotates in a north or westerly directionvoltages will be induced in the tuned circuits -C- and -B- since thecoils 32 and 31 will be positioned at an obtuse angle with relation tothe drive coil 26. These decaying oscillations of voltages induced bythe pulses of current applied to the drive circuit -A- cause a signal tobe induced in the sense circuits -X- and -Y- whose wave forms commencewith a positive peak as shown by FIGS. 7 and 8. The combined wave formof tilt in the north-west direction as seen on the oscilloscope is shownby FIG. 9.

If the tilt of the inclinometer 10 effected by the current is in thesouth or easterly direction the wave forms will be as shown by FIGS. 7and 8 respectively except that the wave forms commence with a negativepeak as shown by FIGS. 10 and 11 with FIG. 12 showing the combined waveforms of the tilt of the inclinometer in the south-easterly direction asshown on an oscilloscope. FIG. 13 shows the wave form for the tilt ofthe inclinometer in the north-east direction, while FIG. 14 shows thewave form for the tilt of the inclinometer in the south-west direction.It can readily be noted that the inclinometer shown by FIG. 15 iscapable of indicating the two directions of tilt that, when combined,indicate the precise direction and magnitude of the current beingmeasured by the inclinometer.

What I claim as new and desire to secure by Letters Patent is: 1.Apparatus for sensing the direction and amplitude of tilt of aninclinometer for measuring the force velocity and direction of a currentof a body of water movement comprising a cylindrical housing having endcaps thereon, a spherical housing contained within said cylindricalhousing, said spherical housing attached to an end cap a movable spherewithin said spherical housing, a fluid contained within said sphericalhousing maintaining said sphere in spaced relation to said sphericalhousing, means for tethering said cylindrical housing in a body ofwater, a bar magnet mounted within said sphere below the center ofgravity of said sphere, the center of gravity of the sphere and thecenter of gravity of the magnet defining a line which is perpendicularto the magnet for maintaining said sphere in a vertical position andoriented toward the magnetic north pole, the combination comprising aplurality of tuned circuits of different resonant frequencies mounted ingreat circles about said sphere and at substantially right angles toeach other, each of said tuned circuits consisting of a plurality ofcoil windings connected in series with a capacitor, one of said tunedcircuits lying in a common plane with said magnet, a drive coil mountedon said spherical housing at right angles to each of said tuned circuitsand lying in a plane substantially parallel to that of said magnet whensaid cylindrical housing is positioned in an upright position, means forapplying an impulse of electric current to said drive coil whereby avoltage impulse is induced in said tuned circuits causing said tunedcircuits to oscillate inducing signals in said drive coil that indicatethe amount of tilt of said cylindrical housing with relation to saidsphere and further means for distinguishing the directions of tilt ofsaid cylindrical housing.
 2. The structure as recited by claim 1 whereinsaid further means comprises a plurality of photosensing devices on saidspherical housing and directed toward each other, said photosensingdevices being positioned substantially at the intersections of saidtuned circuits when said cylindrical housing is in upright position, thesurface of said sphere being divided into optically contrastingquadrants, whereby in conjunction with the photosensing devices thedirection of the inclination can be ascertained when said cylindricalhousing is tilted.
 3. The structure as recited in claim 2 wherein saidfurther means comprises a plurality of sense coils mounted on saidspherical housing in substantial coplanar relation with said coils ofsaid tuned circuits.
 4. The structure as recited in claim 3 wherein saidtethering means comprises said cylindrical housing, said sphericalhousing mounted in said cylindrical housing with the axis of saidcylindrical housing passing through the center of said sphericalhousing, and securing means extending from said cylindrical housingpermitting said apparatus to incline in the direction of the water flowand to the degree of inclination caused by the force of the water flow.